Question 31·Easy·Command of Evidence
Moons of Dwarf Planets
| Dwarf planet name | Number of moons | Name of moons |
|---|---|---|
| Haumea | 2 | Hi‘iaka, Namaka |
| Ceres | 0 | N/A |
| Makemake | 1 | MK 2 |
| Eris | 1 | Dysnomia |
| Pluto | 5 | Charon, Nix, Kerberos, Styx, Hydra |
Like Earth, some dwarf planets in the solar system have exactly one moon. Two examples of such dwarf planets are ______
Which choice most effectively uses data from the table to complete the statement?
For table questions like this, first restate the condition in simple terms (here, “exactly one moon”), then look only at the column that matches that condition. Mark or mentally note all rows that satisfy it, convert them into a short list, and finally choose the answer that matches your list exactly. Ignore any outside facts you know about the topic and rely only on the data given in the table.
Hints
Focus on the key phrase
Underline or mentally note the phrase “exactly one moon.” You are not looking for zero moons or more than one moon—only planets with 1 moon.
Use the correct column in the table
Look only at the “Number of moons” column and find which dwarf planets have the number 1 in that column.
Turn the table into a short list
Write down or say to yourself the names of the dwarf planets that have 1 moon, then find the answer choice that lists exactly those two names together.
Step-by-step Explanation
Identify what the question is asking for
The question says: “Like Earth, some dwarf planets … have exactly one moon.” You need to find two dwarf planets in the table that each have exactly 1 moon and then select the answer choice that lists that pair.
Use the “Number of moons” column
Look down the “Number of moons” column in the table:
- Haumea: 2
- Ceres: 0
- Makemake: 1
- Eris: 1
- Pluto: 5
You are only interested in the rows where the number is exactly 1.
List the dwarf planets that have exactly one moon
From the list, the dwarf planets with exactly one moon are:
- Makemake (1 moon)
- Eris (1 moon)
These are the only two that match the “exactly one moon” requirement.
Match your list to the answer choices
Now check which answer choice includes both Makemake and Eris and no other dwarf planet:
- A) Haumea and Eris → Haumea has 2 moons, so this does not work.
- B) Pluto and Haumea → Pluto has 5 moons, Haumea has 2, so this does not work.
- C) Eris and Makemake → both have exactly 1 moon, which matches the table.
- D) Makemake and Ceres → Ceres has 0 moons, so this does not work.
Therefore, the correct answer is Eris and Makemake.